Then simply ask them if the kens is K-mount of M42 screwmount. If they say K, no adapter needed - but read the sticky thread on using manual lenses in the beginner's forum. If they say M42, then you need the screwmount adapter. If they don't know, don't buy the lens, as the fact they don't know what kind of mount it is means they also have no idea if it works.
There are flange mount adapters which also do the same job as the M42 adapters (be able to attach the screw mount to "K" camera mount) but it doesn't sit it flush on the camera body since there is a flange. The lens registration would be off by a millimeter or so and when this happens, when the lens is set to focus to the horizon (infinity, the lens has the horizontal figure "8" at the end of the focus ring), you won't get focus on that.
It would only focus to about 50 meters or so but not beyond that.